Short version. I load() data in a package. Previously, a test in a package passed, now it fails because the output of sort changed.
Here is a minimal reproducible example - for details see below:
y <- c("Schaffhausen", "Schwyz", "Seespital", "SRZ")
sort(y)
# OLD 3.5.2 [1] "Schaffhausen" "Schwyz" "Seespital" "SRZ"
# NEW 4.0.0 [1] "SRZ" "Schaffhausen" "Schwyz" "Seespital"
# Update 4.0.2 see comment:
# [1] "Schaffhausen" "Schwyz" "Seespital" "SRZ"
# From jay.sf's comment
sort.int(y, method="radix")
# [1] "SRZ" "Schaffhausen" "Schwyz" "Seespital"
sort.int(y, method="shell")
# [1] "Schaffhausen" "Schwyz" "Seespital" "SRZ"
# From Henrik's comment:
data.table::fsort(y)
# [1] "SRZ" "Schaffhausen" "Schwyz" "Seespital"
The only related reported change I found is
CHANGES IN R 4.0.0
NEW FEATURES
...
When loading data sets via read.table(), data() now uses LC_COLLATE=C to ensure locale-independent results for possible string-to-factor conversions.
But I am even not sure, if this could explain what I see.
As I want to minimize the number of imported packages and I would like to understand what's going on, I am not sure how to proceed. Do I miss something?
(A change to a sort.int with method radix would do the job, but still: Why did it change? Is that really better?
I just realized, that (thanks to Roland) sort calls in my case sort.int:
function (x, decreasing = FALSE, na.last = NA, ...)
{
if (is.object(x))
x[order(x, na.last = na.last, decreasing = decreasing)]
else sort.int(x, na.last = na.last, decreasing = decreasing,
...)
}
From ?sort.int:
The "auto" method selects "radix" for short (less than 2^31 elements) numeric vectors, integer vectors, logical vectors and factors; otherwise, "shell".)
And according to the docs, sort.int did not change from 4.0.0 to 4.0.2.
From ?data.table::setorder
data.table always reorders in "C-locale". As a consequence, the ordering may be different to that obtained by base::order. In English locales, for example, sorting is case-sensitive in C-locale. Thus, sorting c("c", "a", "B") returns c("B", "a", "c") in data.table but c("a", "B", "c") in base::order. Note this makes no difference in most cases of data; both return identical results on ids where only upper-case or lower-case letters are present ("AB123" < "AC234" is true in both), or on country names and other proper nouns which are consistently capitalized. For example, neither "America" < "Brazil" nor "america" < "brazil" are affected since the first letter is consistently capitalized.
Using C-locale makes the behaviour of sorting in data.table more consistent across sessions and locales. The behaviour of base::order depends on assumptions about the locale of the R session. In English locales, "america" < "BRAZIL" is true by default but false if you either type Sys.setlocale(locale="C") or the R session has been started in a C locale for you – which can happen on servers/services since the locale comes from the environment the R session was started in. By contrast, "america" < "BRAZIL" is always FALSE in data.table regardless of the way your R session was started.
(Related questions Language dependent sorting with R and Best practice: Should I try to change to UTF-8 as locale or is it safe to leave it as is?)
Details
R.version # old _
platform x86_64-w64-mingw32
arch x86_64
os mingw32
system x86_64, mingw32
status
major 3
minor 5.2
year 2018
month 12
day 20
svn rev 75870
language R
version.string R version 3.5.2 (2018-12-20)
nickname Eggshell Igloo
y <- c("Schaffhausen", "Schwyz", "Seespital", "SRZ")
sort(y)
# [1] "Schaffhausen" "Schwyz" "Seespital" "SRZ"
stringr::str_sort(y)
# [1] "Schaffhausen" "Schwyz" "Seespital" "SRZ"
stringr::str_sort(y, locale = "C")
# [1] "SRZ" "Schaffhausen" "Schwyz" "Seespital"
# =======
R.version # new after upgrade
platform x86_64-w64-mingw32
arch x86_64
os mingw32
system x86_64, mingw32
status
major 4
minor 0.0
year 2020
month 04
day 24
svn rev 78286
language R
version.string R version 4.0.0 (2020-04-24)
nickname Arbor Day
y <- c("Schaffhausen", "Schwyz", "Seespital", "SRZ")
sort(y)
# [1] "SRZ" "Schaffhausen" "Schwyz" "Seespital"
stringr::str_sort(y)
# [1] "Schaffhausen" "Schwyz" "Seespital" "SRZ"
stringr::str_sort(y, locale = "C")
#[1] "SRZ" "Schaffhausen" "Schwyz" "Seespital"
# ==== Test with new 4.0.2
R.version
platform x86_64-w64-mingw32
arch x86_64
os mingw32
system x86_64, mingw32
status
major 4
minor 0.2
year 2020
month 06
day 22
svn rev 78730
language R
version.string R version 4.0.2 (2020-06-22)
nickname Taking Off Again
y <- c("Schaffhausen", "Schwyz", "Seespital", "SRZ")
sort(y)
# [1] "Schaffhausen" "Schwyz" "Seespital" "SRZ"
stringr::str_sort(y)
# [1] "Schaffhausen" "Schwyz" "Seespital" "SRZ"
stringr::str_sort(y, locale = "C")
# [1] "SRZ" "Schaffhausen" "Schwyz" "Seespital"